PULSED
MIG CLAD AND OVERLAY WELDS:
I
hope your company does not make Clad MIG welds like this.
Above
Photo: This sad approach to placing welds on boiler water wall tubes, was
proudly displayed on the cover of a 2008 USA welding magazine. The magazine clad
article was about the wonderful, new, 2008 pulsed MIG equipment available from
Miller Electric and the suitability of this equipment to this Inconel clad application.
The reality is, these clad stringer welds indicate, bad weld practices, this is
not the way to produce water wall clad welds with either Inconel or Stainless
MIG weld wires.
The clad welds in the photo reveal a poor pulsed MIG program,
poor clad weld practices and poor weld techniques. These narrow, clad welds
will create inconsistent, unnecessary weld over lap, poor and excess weld tie
ins, inconsistent clad dilution, excess start stops, and their will be extensive
lack of clad weld fusion. This operation will result in excess distortion, uneven
wear, unnecessary stress risers all leading to reduced boiler operation efficiency
and longevity..
Ed's
USA / European patented MIG weld process control approach to water wall
clad
welds, with a $5000 (2005) pulsed power source. 
Inconel
622 on Boiler Water Walls.
Ed's contribution to the
Power and
Waste Management Industries.
2007:
Welding Services (WSI) Atlanta: WSI is primarily involved in repairs and  refurbishment
in the power, waste energy and nuclear industries. In terms of water wall
clad welding, WSI has clad approx. 80% of the North American boilers. Each year
WSI uses approx. one million pounds of Inconel 625-622 and 300 series stainless
MIG wires for cladding boiler water wall tubes.
CREATED
A NEW PATENT: While WSI has produced some of the most innovative, automatic
MIG cladding equipment available in North America, WSI did not have a resident
MIG process control expert who had the expertise necessary to make radical improvements
to it's water wall clad MIG welds. Ed was contracted for this work by the WSI
engineering manager. In less than 6 months, as the following pictures indicate,
Ed dramatically improved the water wall overlay weld quality and a new USA and
European clad weld patent was developed.
WITH ALL CLAD WELDS LESS IS ALWAYS BETTER:
 IMPROVED
BOILER LIFE AND OPERATING EFFICIENCY:
As
many in the power industry are aware, with any clad weld application "less
is always better". The boilers operate more efficiently when the single pass
clad weld surface is thinner and the clad weld pass thickness is uniform and free
of weld defects. When the clad filler metals cost over $22 a pound, you don't
want to waste this product. Ed's new clad patent dramatically
improved the single pass clad weld quality and dramatically
reduced the typical
single pass clad weld thickness:
DRAMATIC
REDUCTION IN CONSUMABLE WELD COSTS PER-OPERATION. With Inconel clad wires at $22
per-pound and large areas to be clad, weld consumable
costs are typically a large part of the cost of a boiler clad application. Ed's
new procedure reduced the amount of clad single pass, clad
weld overlay by approx. 28%.
SINGLE
PASS CONTROLLED CLAD WELD DILUTION: With
water wall clad applications, the minimum, "single pass" Inconel weld
clad chemistry required is 20% chrome. To attain the minimum chrome requirements,
the pulsed MIG weld procedures with the vertical down clad welds consistently
attained minimum weld dilution < 8%, while achieving consistent weld fusion
on the carbon steel boiler tubes.
ATTAINED
HIGH DEPOSITION RATES: The
primary part of clad weld costs on large weld areas as found with most clad boiler
wall applications is dictated by
the MIG weld deposition rates attained. Ed's new patented clad procedure with
the unique, WSI automated weld equipment, enabled a single operator controlling
two guns to deposit approx. 28 lbs/hr.
Unless
you sell clad weld consumables,
with
clad welds on boilers, less is always better.
Before
Ed got involved with water wall welds the picture below was considered an
optimum, Inconel 622,
Vertical Down, Pulsed MIG Clad MIG weld.
After
a few months of pulsed MIG weld process development.
The final Inconel 622,
single pass, clad
weld results were
developed by Ed for WSI in 2006.
Note the smooth single layer MIG clad surface with optimum weld ties ins. This
clad application was delivered from a low cost, $5000 pulsed MIG power source
in 2006. This clad weld has a smooth finish similar to a $250.000 laser - powder
clad overlay. In contrast to the conventional water wall clad welds, Ed's process
changes required 25% less weld metal per sq/ft and for the single pass weld also
produced less weld dilution producing superior clad chemistry.
SPATTER WITH ANY MIG MODE IS USUALLY AN
INDICATION OF LACK OF PROCESS CONTROL
Weld
process expertise will always ensure that any
weld process utilized runs
without concern for weld spatter.
.
2006: Ed's patented weld on the left.
Typical clad welds on the right:
A
CLAD MIG GAS MIX DEVELOPED BY ED
The
vertical down 622 Inconel / stainless clad MIG welds were derived from a low cost,
six thousand dollar pulsed MIG power source and a MIG gas
mix developed by Ed. (See the MIG gas data section at this site). These
welds also required an engineering manager that believed that there was more to
MIG welding than asking the advice of a Lincoln / Miller sales rep or an operator
throwing a switch that initiates the clad welding arc.
It
also helped that WSI had excellent, unique automated weld equipment that compensated
for the wire stick
out variations from the water wall curves. Ed's clad
development was complete in 2006 and WSI applied for the Patent during 2006 -
2007.
How can any respectable engineer allow $22 a pound Inconel single clad welds
like this on a power
station product that costs million of dollars?.
.
Cladding
and Hydro-Processing Vessels
2006:
Another common global clad application
overlay application influenced by Ed:
The
Electro Slag Strip Electrode Process
applying ER 347 clad welds.
The
Electro Slag Common Application. In
the refinery industry, pressure vessels used in high temperature, high pressure
"hydrogen service" such as hydrocracking and hydrotreating are usually
constructed of Chrome / Molly or Vanadium modified Chrome / Moly steels. To overcome
corrosion areas with these vessels, clad welds of ER 347 alloy are typically applied
to plate or to wasted
areas on pressure vessels.
The most common, global cladding "process"
utilized for plate cladding used for hydrogen service, has been the Electro Slag
Welding (ESW). This process uses strip electrodes two to three inches wide. On
some applications a butter layer of ER 309 is requested followed by a surface
layer of ER 347 for the clad surface. On other applications a single layer of
ER 347 is applied.
With
the ESW process, high deposition welds result from weld current > 600 amps.
The ESW process has been considered unique in that the large size of the strip
electrode results in low weld current density resulting in "low weld dilution".
The down side of this process is;
[a]
its a "single" electrode process,
[b] It's large, cumbersome
and weld position restricted,
[c] the cost of the clad consumables and
flux are high,
[d] there are few companies with expertise. Many North
American vessels are clad in Japan.
Utilizing
a unique MIG weld wire found by Ed, and cladding equipment developed by WSI, has
enabled the ability to produce "single pass", MIG layer clad 347 welds
that meet the hydrogen service 347 clad thickness, chemistry and ferrite requirements.
In comparison to the ESW and SAW process, thanks to the large differences in consumable
costs and the multi MIG gun capability, it's now possible to produce the 347 MIG
clad welds, depending on the application with a 30 to 50% cost reduction.
In
contrast to the much more costly ESW and SAW processes, the single pass MIG clad
procedure developed by Ed and WSI enables cladding on a much wider range of applications,
and allows the flexibility to provide the vessel cladding at any site locations.
This dramatically reduces the vessel lead times or shipping costs to have this
work done.
ED'S
MIG PROCESS CONTROL EXPERTISE CHANGED THIS TRADITIONAL
GLOBAL 347 ELECTRO
SLAG AND SAW WELD CLAD APPLICATION.
 
To
a clad MIG process that's faster, provides less distortion,
has less heat
effect on the steel, costs less and is much more versatile.
Ed's MIG
Clad Welds Made in the 1980's.
In
the 1980s, long before the development of pulsed MIG, Ed produced the Inconel
622 MIG clad weld shown in the left photo (cross section of a boiler tube). In
his clad weld there was no metallurgical evidence of a heat affected zone as evidence
in the macro. On the right photo is the typical MIG clad
weld fusion profiles
that the power industry was accustomed to in 2008.
Ed's
Inconel clad weld on the left was made
without any cooling medium and made
with a MIG process developed in 1963.
622
and a Unique Controlled Short Circuit Clad Weld made 1983
This
622 MIG clad weld made by Ed and and his good buddy Zugy, surprised the Foster
Wheeler metallurgist who examined it, as their was no evidence of the 622 weld
dilution with the carbon steel base alloy, and no evidence of a weld's heat affected
zone.
We
never had MIG equipment bells and whistles in the 1980s, yet we did have weld
process expertise and low cost MIG weld equipment developed in the 1960s. In those
days we were producing welds that are still are not produced 30 years later. In
1980 if you wanted a small vessel made from aluminum bronze you ordered a solid
bar stock and spent many hours ID and OD machining, or you had it cast at a foundry
and waited 3 or 4 months. Of course you could have or called Ed and his good buddy
Zugy and they would show you how with a few pounds on alum bronze 0.045 weld wire,
in a few hours you could make the part strictly out of weld metal. If you needed
a small vessel comprised of two different alloys such as the one show above, in
which one half was Hastelloy and the other half was 316 stainless you could have
spent weeks figuring out how to make it and a small fortune in machining or you
could have called Ed and Zugy and in less than a day the product would have been
made from Hastelloy and stainless weld wire. Of course if you wanted to find the
holy grail of welding, Ed and Zugy would have taken some Titanium weld wire and
in three hours made the above chalice free of defects from a Titanium MIG weld
wire.
Today
we will go where no man has gone before,
 
however
if you have to take weld advice from salesman, or your weld
personnel "play"
with weld settings, the consequences can be costly...
When
you have a clad welding challenges on those ID-OD power plant, refinery, and well
head equipment such as ID welds on adapter flanges,bonnets, studded tees, tree
caps, weld neck flanges, gate valves, please note, you can invest hundreds of
thousands of dollars in sophisticated overlay equipment and never quite get that
application the way it could be. You could ask a salesman for your pulsed clad
MIG advice, or you could learn how to control this important process
and produce clad welds without weld rework.
Russia
solves their auto engine problems.  A
Russian fuel efficient one horse car.
Your keys to MIG weld process
optimization:
If
you are teaching your self, or providing weld process control training for others,
the following resources are the key to attaining MIG and flux cored weld process
optimization. Note: Items 2-3-4 are
the most comprehensive process control,
self teaching and training programs ever developed..
Item.1.
The Book: "A Management & Engineers Guide To MIG Weld
Quality, Productivity & Costs"
Item
2. A unique robot MIG training or self teaching
resource. "Optimum Robot MIG Welds from Weld Process Controls".
Item
3. A unique MIG training or self teaching resource.
" Manual MIG Weld Process Optimization from Weld Process Controls".
Item.
4. A unique flux cored training or self teaching resource.
"Optimum Manual and Automated Flux Cored Plate and Pipe welds.
Item
5a."Proceso de Soldadura MIG Manual" (MIG Made Simple. Self
teaching in Spanish)
Item
6a. The Self Teaching MIG Book / Video. (MIG
Made Simple in English).
Visit
Ed's MIG / flux cored process control books and CD training
resources.
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